Same bubbles.
Different fermentation.
Different finish.

Mumm Brut Rosé and La Marca make different sparkling-method arguments, not a clearly better one. Public reception reads 92–94.

Mumm Brut Rosé uses the traditional method: a second fermentation happens inside each sealed bottle, and the producer states an average 16 months resting on the spent yeast before dosage, applied to a 76% Pinot Noir, 22% Chardonnay and 2% Pinot Meunier blend with published 12.5% ABV, 7.1 g/L acidity, pH 3.12 and 10.4 g/L dosage. La Marca uses the Martinotti-Charmat tank method: the second fermentation happens in a pressurized tank rather than the bottle, the standard Prosecco DOC approach for a Glera-led wine with pear, apple, citrus and floral fruit, and this record does not yet confirm whether the shelf bottle is labeled Brut or Extra Dry. Choose Mumm Brut Rosé when bottle-aged structure, red-fruit depth and a drier, more toast-inflected finish are the point; the producer's own record calls this a step up from tank-fermented bubbles. Choose La Marca when an easy, fruit-led tank-method aperitif is the assignment; its own record recommends passing on it if bottle-aged complexity is what you actually want.